Which of the following would be a typical behavior at one month old?

At one month old, infants typically exhibit jerky arm movements as part of their developing motor skills. This behavior is a reflection of their immature nervous system, where muscle coordination is not yet fully refined. The movements are often uncoordinated and sporadic as they are still learning how to control their limbs. This characteristic is common and indicates normal development at this early stage.

Children at this age may not yet show the ability to hold objects or recognize parents' faces reliably. Grasping is a reflex that may happen but is not consistent or intentional. Turning the head towards sound is also a behavior that usually begins to emerge a bit later as hearing and body coordination improve. Thus, jerky arm movements are a representative behavior for infants at this stage of development.